Final question before I send it back ( again) to the repair shop.

Anyone has experience with a sticky aperture?
Ive been struggling with my 24-70 2.8 Sigma lens for the past 8 months, I had it for the over 5 years now and I love that lens it has been very good to me.
Sometimes I shoot 40 shots everything is fine and other time 2 shots and the aperture get stuck.
I sent it to Sigma New York but they could not see anything wrong, they sent it back to me and the lens was fine for a couple months. Now the viewfinder get dark after 2-5 shots.
All I have to do is to barely unscrew the lens then screw it back and voila clear viewfind ready to shoot 1-3 shots. I cleaned up the contact, but didnt do much

I know I know its time to send it back to the repair shop but anyone has similar experience???

Thanks

I have the Sigma 17-35 f2.8 (82mm filter size) and the exact thing just started happening!
I think I have to agree that it is a sticky aperture. My auto focus just rotates from side to side, unable to lock on anything when it acts up, and the viewfinder gets very dark light someone turned out the lights... sometimes I can simply remove the lens and put it back, and it works for 3 or 4 more shots. sometimes just powering off and on will do it, most of the time it requires a lot of cussing and yelling at it to get it working again,
No Idea how much to repair something like this yet, and I have not found a solid solution yet, but I am working diligently on it...

After much more research, I have at least diagnosed the problem, It is definately a sticky apeture. I can look through the lens (un-attached from the camera) and see when it is supposed to be wide open, it is almost completely closed. I attached it to the camera, set it to f/4,(for some reason, that is open as it would go) and very gently tapped on the body of the lens with my fingers, and it popped right open! it has given me about 40 pictures so far, and has not stuck closed again yet, and it is stopping all the way to 2.8 again...
Appearently, it just needs to be cleaned at the blade level.
I'll post if it messes up again, or I take it in for repair...

Did you send your lens to Sigma USA in Ronkonkoma, NY or to Chandler, AZ? The company in AZ is under contract with Sigma and perhaps you'd have better success with Sigma directly in NY. I've brought a few items in personally and they always take care of my problems.

Originally Posted by ntotrr Did you send your lens to Sigma USA in Ronkonkoma, NY or to Chandler, AZ? The company in AZ is under contract with Sigma and perhaps you'd have better success with Sigma directly in NY. I've brought a few items in personally and they always take care of my problems.

Sorry, I see you did send in to NY.

Got exact same problem with same lens! Sigma f2.8 24-70 EX DG etc. Has worked fine for 5 years since I got it, casual use as I found it a difficult range in the end but still love the lens, but have it here in Italy with me and after 10,000 shots in the last week, not only has the focus failed (it prevents focusing below 5feet), but the aperture has become incredibly sticky to the point that it's now stuck closed at around f6.3ish.

Very annoyed and a Canon 15-85 is on it's way out here to replace it!

Originally Posted by jdroest Got exact same problem with same lens! Sigma f2.8 24-70 EX DG etc. Has worked fine for 5 years since I got it, casual use as I found it a difficult range in the end but still love the lens, but have it here in Italy with me and after 10,000 shots in the last week, not only has the focus failed (it prevents focusing below 5feet), but the aperture has become incredibly sticky to the point that it's now stuck closed at around f6.3ish. Very annoyed and a Canon 15-85 is on it's way out here to replace it!

Sorry to hear about the Sigma problems, but congratulations on the Canon EF-S 15-85mm f/3.5-5.6 IS USM UD.

In good light that 15-85mm zoom has some very nice properties.

Originally Posted by ziggy53 Sorry to hear about the Sigma problems, but congratulations on the Canon EF-S 15-85mm f/3.5-5.6 IS USM UD. In good light that 15-85mm zoom has some very nice properties.

Obsessively checking the DHL tracking number now :) Really looking forward to the better focal range. Gonna miss f2.8 though, but i'm purely doing outside work so it should be ok.

Question is - what to do with the Sigma though. Repair and Ebay it?

Absolutely love this 15-85! Got it last night and spent the day with it. Wish I had bought it sooner!